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From: Rico Pajarola <rp@servium.ch>
To: Noel Chiappa <jnc@mercury.lcs.mit.edu>
Cc: The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: Re: [TUHS] Set-uid shell scripts
Date: Sun, 4 Aug 2019 09:50:32 -0700	[thread overview]
Message-ID: <CACwAiQkMFrjtY5f1iA5ihd3tQiW=FKqvY1UEKy6SM_Q3zoQqMQ@mail.gmail.com> (raw)
In-Reply-To: <20190804155854.C22CA18C096@mercury.lcs.mit.edu>

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when running a shell script, what's actually executed is the first line of
the script (after #!) + the name of the script.

If your script is named "-i", and in your path, just enter "-i", and
/bin/sh -i is executed which gives you an interactive shell.

There are probably half a dozen other ways to trick the shell into
executing arbitrary code that is not contained in the script (more if the
script actually does anything non-trivial, like e.g. an installer of some
sort). So instead of trying to fix them all (and most likely missing a
few), everybody just agreed that it was a terrible idea and removed the
feature.


On Sun, Aug 4, 2019 at 9:00 AM Noel Chiappa <jnc@mercury.lcs.mit.edu> wrote:

>     > From: Alec Muffett
>
>     > until someone realised that you could do:
>     >  ln -s /bin/scriptname ./-i
>     >  "-i" # assuming that "." is already in your path
>     > ...and get a root shell.
>
> I'm clearly not very awake this morning, because I don't understand how
> this
> works. Can you break it down a little? Thanks!
>
>        Noel
>
>

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  parent reply	other threads:[~2019-08-04 16:51 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-04  7:36 Dave Horsfall
2019-08-04  7:43 ` Alec Muffett
2019-08-04 15:58   ` Noel Chiappa
2019-08-04 16:30     ` Michael Kjörling
2019-08-04 16:48       ` Alec Muffett
2019-08-04 17:48         ` Michael Kjörling
2019-08-04 19:45           ` Alec Muffett
2019-08-04 16:50     ` Rico Pajarola [this message]
2019-08-04  7:46 ` arnold
2019-08-04 20:18 Noel Chiappa
2019-08-04 20:29 ` Clem Cole
2019-08-04 20:42   ` Richard Salz
2019-08-04 23:58 ` Dave Horsfall
2019-08-04 21:18 Norman Wilson
2019-08-04 21:27 Norman Wilson
2019-08-06  8:28 ` jason-tuhs
2019-08-06  9:55   ` arnold
2019-08-06 22:48   ` Dave Horsfall
2019-08-06 22:56     ` ron minnich
2019-08-07  1:21     ` Dave Horsfall
     [not found]       ` <40c92e85142fe7e3@orthanc.ca>
2019-08-07 21:33         ` Dave Horsfall
2019-08-08  6:39           ` Peter Jeremy
2019-08-07 12:56     ` Chet Ramey
2019-08-07 21:40       ` Dave Horsfall
2019-08-08  5:16         ` Adam Thornton
2019-08-14  5:41           ` Efton Collins
2019-08-05  0:13 Noel Chiappa

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